Conventionally, attempts have been made to provide electric and electronic components such as motor and transformer cores having higher densities and smaller sizes to meet the demand for more precise control using small electric power, which has lead to development of soft magnetic materials used in fabricating such electric and electronic components which provide improved magnetic properties particularly in the middle to high frequency range.
In conjunction with such soft magnetic materials, Japanese Patent Laying-Open No. 2002-246219, for example, discloses a dust core in which magnetic properties can be maintained during use in high temperatures and a method of manufacturing such a core (Patent Document 1). According to the method disclosed in Patent Document 1, an atomized iron powder covered with a phosphate film is first mixed with a predetermined amount of polyphenylene sulfide (PPS resin) and then undergoes compression molding. The resulting molding is heated in air at a temperature of 320° C. for one hour and then heated at a temperature of 240° C. for another hour. It is then cooled to fabricate a dust core.
Patent Document 1: Japanese Patent Laying-Open No. 2002-246219